David Liaw

About the Event

Over the last few years, there has been growing interest in a new class of space propulsion for smaller satellites in lower Earth orbit that utilize highly charged and accelerated nanoparticles (Nanoparticle Field Extraction Thruster or NanoFET) or liquid droplets (colloidal thrusters) to provide thrust. As with any electric propulsion system that emits charged particles, an issue to be examined is how to ensure charge neutral operation. Specifically, this work investigates potential methods to self-neutralize or use the surrounding ambient ionospheric plasma to avoid the complexity of an additional neutralization sub-system.
Plausible options to neutralize NanoFET and colloidal thrusters with as little increase in complexity as possible are to emit equal amounts of oppositely charged particles by either (i) simultaneous emission from separate locations (ii) emission from a single location with periodic polarity change, or (iii) emission of a negatively charged nanoparticle beam into a background plasma that can provide an electron return current.
Even smaller than the satellites that NanoFET and colloidal thrusters are envisioned for providing propulsion to are a class of satellites called femtosatellites. Femtosatellites require unconventional means of propulsion due to their low mass, power, and size budget, with one possible propulsion technique being electrodynamic tethers. An area of study for the electrodynamically tethered femtosatellite system is the electron emission scheme either through a field emitter array cathode or a thermionic cathode/hot filament.
This thesis investigates all of these neutralization methods primarily through simulation.